Grey squirrel (Sciurus carolinensis)
The grey squirrel was introduced from North America between 1876 and 1929. The species can be found throughout Somerset in woodlands, parks and gardens. Active throughout the day, grey squirrels have a very varied diet, including tree seeds such as acorns, hazelnuts, beech mast and pinecones, as well as invertebrates, fungi, small mammals, bird eggs and nestlings.
Unfortunately for woodland owners or anyone wanting to plant a new woodland, grey squirrels will readily strip the bark off young trees, often causing damage that the tree cannot survive or even killing it outright. Grey squirrels are also known for their habit of storing of food for the winter, and can be seen hiding caches of nuts underground which can be drawn on throughout the winter. The species has two breeding seasons in the UK, one in the spring and the second in late summer, with litters of 1-7 young.
Look out for signs of grey squirrels in woodland by searching for hazelnuts that have been split in half, striped pine cones or trees with patches bark ripped off. Their nests, known as dreys, often resemble a clump of dead leaves wedged in the fork of a tree branch.
Muntjac deer (Muntiacus reevesi)
Muntjac deer, also known as Reeves’ muntjac, are a small deer species native to China. They were first introduced to the UK in Bedfordshire in 1901 and have since spread across England, with sightings now common in Somerset.
Measuring only about half a metre high, Muntjac deer are short and stout with a hunched appearance that is almost pig-like. Males and females look very similar apart from the males’ short, single spike antlers. These antlers are shed between April and May, and grow back throughout the summer. Although difficult to see, males also have protruding canines - think fangs!
Muntjac are often secretive and prefer to stay within woodland during the day. Both sexes are territorial, and will defend their territories from others. Unlikely other deer species, Muntjac can breed year-round with females coming into season shortly after giving birth.
Muntjac are selective browsers, eating leaves and flowers, as well as nuts and fungi in the autumn. However, the species can have a detrimental impact on woodland habitats, as they browse the woodland ground flora, including bluebells and primrose ,as well as tree seedlings and regrowth from recently coppiced trees, often killing them. Woodland with muntjac will often have an obvious browse line at 60-80cm, with little vegetation below.
Fallow deer (Dama dama)
Fallow deer were introduced to the UK in the 11th century for hunting and have since become widespread. Often the deer of choice for deer parks, Fallow deer are an attractive medium sized deer with a reddish-brown coat covered in white spots. From August the males have distinctive flattened antlers, which fall off around April and begin to regrow.
Fallow deer prefer a mixture of woodland and open fields, and can often be found in parkland. Mainly a grazing species, their diet is predominantly grass, supplemented with leaves from trees and shrubs, as well as acorns or other nuts in the autumn.
The Fallow deer rut takes place in October and early November. Males establish rutting stands to attract females similar to lekking seen in other species. Females give birth to a single fawn in May/June.
American mink (Neovison vison)
The American mink was farmed in the UK for its fur from the mid-20th century, and is now found widely in the wild due to escapees and releases. American mink look similar to a stoat or polecat, but have black or dark brown hair and tend to be found close to watercourses. Excellent swimmers, they can dive to 5-6m and travel long distances underwater.
American mink have a broad diet and will take fish, water voles, birds, eggs and nestlings, as well as crustaceans along watercourses, meaning they often have a detrimental impact on native riparian wildlife.
Over the years American mink have been subject to intensive trapping efforts, but remain a significant pest species in the UK. There has been a decline in numbers in recent years due to the recovery of otter populations, which act as competing species and push the mink out